US4163570A - Optically coded document and method of making same - Google Patents

Optically coded document and method of making same Download PDF

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Publication number
US4163570A
US4163570A US05/848,871 US84887177A US4163570A US 4163570 A US4163570 A US 4163570A US 84887177 A US84887177 A US 84887177A US 4163570 A US4163570 A US 4163570A
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United States
Prior art keywords
relief structure
information carrier
surface relief
markings
shape
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Expired - Lifetime
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US05/848,871
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David L. Greenaway
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Siemens Building Technologies AG
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LGZ Landis and Gyr Zug AG
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    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/002Recording, reproducing or erasing systems characterised by the shape or form of the carrier
    • G11B7/0033Recording, reproducing or erasing systems characterised by the shape or form of the carrier with cards or other card-like flat carriers, e.g. flat sheets of optical film
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06KGRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K1/00Methods or arrangements for marking the record carrier in digital fashion
    • G06K1/12Methods or arrangements for marking the record carrier in digital fashion otherwise than by punching
    • G06K1/126Methods or arrangements for marking the record carrier in digital fashion otherwise than by punching by photographic or thermographic registration
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06KGRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/08Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means
    • G06K19/10Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means at least one kind of marking being used for authentication, e.g. of credit or identity cards
    • G06K19/16Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code using markings of different kinds or more than one marking of the same kind in the same record carrier, e.g. one marking being sensed by optical and the other by magnetic means at least one kind of marking being used for authentication, e.g. of credit or identity cards the marking being a hologram or diffraction grating
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06QINFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
    • G06Q20/00Payment architectures, schemes or protocols
    • G06Q20/30Payment architectures, schemes or protocols characterised by the use of specific devices or networks
    • G06Q20/34Payment architectures, schemes or protocols characterised by the use of specific devices or networks using cards, e.g. integrated circuit [IC] cards or magnetic cards
    • G06Q20/343Cards including a counter
    • G06Q20/3433Cards including a counter the counter having monetary units
    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07FCOIN-FREED OR LIKE APPARATUS
    • G07F7/00Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
    • G07F7/02Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by keys or other credit registering devices

Definitions

  • This invention relates to optically coded documents, i.e., documents comprising an information carrier on which information is recorded in the form of optical markings.
  • Documents such as identity cards, credit cards, pre-paid payment tokens which can be devalued in stages, travel tickets, entry cards and the like, carrying information in the form of optical markings, are known in many different forms. Most known documents of this type can be counterfeited fairly easily.
  • a very high degree of protection against forgery can be obtained if the information is fed into the document in the form of diffraction gratings, holograms or similar light-modifying optical markings.
  • a known document which is used as a pre-paid payment token for obtaining goods or services comprises an information carrier made of thermoplastic material with optical markings impressed in it.
  • the markings, representing units of value, have a structure which modifies incident light by diffraction or refraction.
  • the optical markings are tested for genuineness, and a number of markings corresponding to the amount to be paid is cancelled by fusing or perforating them, scraping them off or otherwise obliterating them.
  • the obliteration process requires a relatively large amount of energy, which in many cases is not readily available.
  • One object of this invention is to provide a document of the above-mentioned type wherein the optical markings can be obliterated or altered in order to change the information with small expenditure of energy.
  • Another object of this invention is to provide a document of the above-mentioned type wherein the information carrier has a shape-memorizing capability.
  • a further object of this invention is to provide a document of the above-mentioned type wherein the information carrier has a shape-memorizing capability which by the application of energy can be caused to change the shape of the information carrier.
  • a document comprising an information carrier on which information is recorded in the form of optical markings, wherein said information carrier has a shape-memorizing capability operable by supplying energy to said information carrier and which shape-memorizing capability thereby produces a change in the shape of said information carrier and of said optical markings.
  • FIG. 1 shows a document
  • FIG. 2 is a section through an information carrier
  • FIG. 3 shows the information carrier of FIG. 2 with an optical marking
  • FIG. 4 shows the information carrier of FIG. 2 with an altered optical marking
  • FIG. 5 is a graph
  • FIG. 6 shows a further information carrier
  • FIG. 7 shows the information carrier of FIG. 6 with an optical marking
  • FIG. 8 shows the information carrier of FIG. 6 with an altered optical marking.
  • reference numeral 1 represents a document which may be an identity card, credit card, travel ticket, check or check card, entry card, a pre-paid payment token which can be devalued in stages, etc.
  • the document 1 comprises an information carrier 2 into which a plurality of optical markings 3 are fed.
  • Each of the markings 3 represents a piece of information about genuineness.
  • An individual piece of information can be put into the document 1 by obliterating certain markings 3', or at least by altering them so that they produce a different optical effect to the unaltered markings 3.
  • the word "obliterate" will hereinafter be used even when the markings 3' are merely altered and not completely obliterated.
  • the markings 3' may be obliterated before the document is issued and/or during its use in a service machine or the like.
  • the information carrier 2 has a shape-memorizing capability which can be put into action by supplying energy.
  • the information carrier 2 In order to feed the individual piece of information into the document 1, the information carrier 2 is exposed to the action of radiation or heat in the region 4 of the markings 3' to be obliterated. This causes the information carrier 2 to undergo a change of shape in the region 4 on the basis of its shape-memorizing capability. This also brings about a change in the shape of the markings 3' and conversion of the information contained in them.
  • All types of materials with a shape-memorizing capability which can be put into action by supplying energy, which thereby change their shape in at least one dimension so that the markings 3' undergo an optically perceptible change of shape, are suitable for the information carrier 2.
  • Materials which are particularly appropriate are thermoplastic ones with an elastic stress field stored in them, where the stress field can be relaxed by the action of heat and thereby produce a change in the shape of the information carrier.
  • the elastic stress field is advantageously put into the information carrier 2 by an impressing process during the production of the markings 3, as will be demonstrated below.
  • FIG. 2 shows the information carrier 2 made of thermoplastic material, in its initial state. Its surface has an irregular relief structure 5 with a random periodicity, for example, of about 30 microns, which causes dispersion of incident light.
  • This matte surface can be produced during the actual manufacture of the information carrier 2 or in a subsequent impressing process, by means of sand-blasted or similarly treated calender rolls or impressing matrices.
  • the optical markings 3 are impressed in the matte surface by applying pressure and heat; in the FIG. 3 example they have a sinusoidal relief structure 6 with a periodicity of a few microns. If the impressing conditions are suitably selected the first relief structure 5 will disappear and be converted into an elastic stress field 7, resulting from the marked change in the shape of the thermoplastic material in the high regions of the relief structure 5 and the slight change of shape in the low regions thereof.
  • the information carrier 2 is heated beyond the glass transition temperature of the thermoplastic material in the region of the markings 3' which have to be obliterated. In this way the elastic stress field 7 is relaxed and the original relief structure 5 re-forms. It has been found that the first relief structure 5 is re-established before the second relief structure 6 disappears so that, given careful selection of temperature, a new relief structure 8 (as in FIG. 4) will appear, corresponding to a superimposed arrangement of structures 5 and 6. This obviously pre-supposes that no pressure or only slight pressure is exerted on the information carrier 2. If the heating element is pressed hard onto the information carrier 2 during the obliteration process, the surface structure of the heating element will be impressed in the carrier.
  • the optical properties of the resultant relief structure 8 are very advantageous. Whereas the relief structure 6 diffracts incident light, relief structure 8 produces diffused dispersion. This ensures that the unchanged markings 3 can be reliably distinguished from the obliterated markings 3' with an optical reading instrument.
  • the information provided by the unchanged markings 3 and the obliterated markings 3' may be read in known manner from the light reflected at the markings 3 and 3'. This is made possible by applying a thin reflective film to the information carrier 2 before or after the relief structure 6 is impressed. It is of course also possible to detect the light transmitted instead of the light reflected.
  • the solution described gives a considerable reduction in the amount of energy required to obliterate the markings 3', and also a greater difference between the optical properties of the obliterated and unobliterated regions.
  • FIG. 5 shows a typical curve of the tensile strength ⁇ B and expansion ⁇ g of a thermoplastic material in dependence on the temperature T.
  • the transition from the solid to the thermoelastic range of states at glass transition temperature T g is characterized by a sharp drop in tensile strength ⁇ B and a steep rise in expansion ⁇ g .
  • the transition from the thermoelastic to the thermoplastic range takes place at flow temperature T f .
  • the second relief structure 6 is advantageously impressed in the carrier 2 in the thermoelastic range.
  • the first relief structure 5 is preferably put into the information carrier 2 in the thermoplastic range. To make the first relief structure 5 reappear it is sufficient to heat the information carrier 2 to a temperature in the region of the glass transition temperature T g ; the energy requirement for obliterating the markings 3' is consequently small.
  • Both the first relief structure 5 and the second relief structure 6 may be of a type such that they diffract, refract or reflect incident light in a characteristic manner, provided that they differ sufficiently from one another.
  • the fineness of the relief structures may extend from Fresnel structures with a periodicity of about 30 microns and more to diffraction structures and holographic relief structures with a periodicity of about one micron.
  • the first relief structure 5 may act as an additional sign of genuineness to safeguard the document 1 against forgeries.
  • FIG. 6 shows a first relief structure 5' of this type, a bevelled profile of sawtooth cross-section.
  • the first relief structure 5' is converted into an elastic stress field 7' (FIG. 7).
  • the relief structure 8' shown in FIG. 8 and produced by the action of heat reflects incident light in a characteristic way similar to the first relief structure 5'.

Abstract

A document is disclosed, which comprises an information carrier in which information is recorded as optical markings. The information carrier has a shape-memorizing capability actuated by supplying energy, such as heat, which changes the shape of the information carrier and the optical markings.

Description

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optically coded documents, i.e., documents comprising an information carrier on which information is recorded in the form of optical markings.
2. Description of the Prior Art
Documents such as identity cards, credit cards, pre-paid payment tokens which can be devalued in stages, travel tickets, entry cards and the like, carrying information in the form of optical markings, are known in many different forms. Most known documents of this type can be counterfeited fairly easily.
A very high degree of protection against forgery can be obtained if the information is fed into the document in the form of diffraction gratings, holograms or similar light-modifying optical markings. For example, a known document which is used as a pre-paid payment token for obtaining goods or services comprises an information carrier made of thermoplastic material with optical markings impressed in it. The markings, representing units of value, have a structure which modifies incident light by diffraction or refraction. When the document is used in a service machine, telephone, etc., the optical markings are tested for genuineness, and a number of markings corresponding to the amount to be paid is cancelled by fusing or perforating them, scraping them off or otherwise obliterating them. The obliteration process requires a relatively large amount of energy, which in many cases is not readily available.
In a document with a plurality of optical markings impressed in thermoplastic material, which modify incident light in a predetermined manner, it has further been proposed to feed in coded information by subsequently obliterating or altering selected optical markings by the action of heat. Here again a relatively large amount of energy is required to obliterate or alter the markings.
SUMMARY OF THE INVENTION
One object of this invention is to provide a document of the above-mentioned type wherein the optical markings can be obliterated or altered in order to change the information with small expenditure of energy.
Another object of this invention is to provide a document of the above-mentioned type wherein the information carrier has a shape-memorizing capability.
A further object of this invention is to provide a document of the above-mentioned type wherein the information carrier has a shape-memorizing capability which by the application of energy can be caused to change the shape of the information carrier.
According to the present invention there is provided a document comprising an information carrier on which information is recorded in the form of optical markings, wherein said information carrier has a shape-memorizing capability operable by supplying energy to said information carrier and which shape-memorizing capability thereby produces a change in the shape of said information carrier and of said optical markings.
The above, and other objects, features and advantages of this invention, will be apparent in the following detailed description of illustrative embodiments which is to be read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a document;
FIG. 2 is a section through an information carrier;
FIG. 3 shows the information carrier of FIG. 2 with an optical marking;
FIG. 4 shows the information carrier of FIG. 2 with an altered optical marking;
FIG. 5 is a graph;
FIG. 6 shows a further information carrier;
FIG. 7 shows the information carrier of FIG. 6 with an optical marking; and
FIG. 8 shows the information carrier of FIG. 6 with an altered optical marking.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, reference numeral 1 represents a document which may be an identity card, credit card, travel ticket, check or check card, entry card, a pre-paid payment token which can be devalued in stages, etc. The document 1 comprises an information carrier 2 into which a plurality of optical markings 3 are fed. Each of the markings 3 represents a piece of information about genuineness. An individual piece of information can be put into the document 1 by obliterating certain markings 3', or at least by altering them so that they produce a different optical effect to the unaltered markings 3. For resons of simplicity the word "obliterate" will hereinafter be used even when the markings 3' are merely altered and not completely obliterated. Depending on the type of document 1, the markings 3' may be obliterated before the document is issued and/or during its use in a service machine or the like.
The information carrier 2 has a shape-memorizing capability which can be put into action by supplying energy. In order to feed the individual piece of information into the document 1, the information carrier 2 is exposed to the action of radiation or heat in the region 4 of the markings 3' to be obliterated. This causes the information carrier 2 to undergo a change of shape in the region 4 on the basis of its shape-memorizing capability. This also brings about a change in the shape of the markings 3' and conversion of the information contained in them.
All types of materials with a shape-memorizing capability which can be put into action by supplying energy, which thereby change their shape in at least one dimension so that the markings 3' undergo an optically perceptible change of shape, are suitable for the information carrier 2. Materials which are particularly appropriate are thermoplastic ones with an elastic stress field stored in them, where the stress field can be relaxed by the action of heat and thereby produce a change in the shape of the information carrier. The elastic stress field is advantageously put into the information carrier 2 by an impressing process during the production of the markings 3, as will be demonstrated below.
FIG. 2 shows the information carrier 2 made of thermoplastic material, in its initial state. Its surface has an irregular relief structure 5 with a random periodicity, for example, of about 30 microns, which causes dispersion of incident light. This matte surface can be produced during the actual manufacture of the information carrier 2 or in a subsequent impressing process, by means of sand-blasted or similarly treated calender rolls or impressing matrices. The optical markings 3 are impressed in the matte surface by applying pressure and heat; in the FIG. 3 example they have a sinusoidal relief structure 6 with a periodicity of a few microns. If the impressing conditions are suitably selected the first relief structure 5 will disappear and be converted into an elastic stress field 7, resulting from the marked change in the shape of the thermoplastic material in the high regions of the relief structure 5 and the slight change of shape in the low regions thereof.
With the aid of a heating element, the information carrier 2 is heated beyond the glass transition temperature of the thermoplastic material in the region of the markings 3' which have to be obliterated. In this way the elastic stress field 7 is relaxed and the original relief structure 5 re-forms. It has been found that the first relief structure 5 is re-established before the second relief structure 6 disappears so that, given careful selection of temperature, a new relief structure 8 (as in FIG. 4) will appear, corresponding to a superimposed arrangement of structures 5 and 6. This obviously pre-supposes that no pressure or only slight pressure is exerted on the information carrier 2. If the heating element is pressed hard onto the information carrier 2 during the obliteration process, the surface structure of the heating element will be impressed in the carrier.
The optical properties of the resultant relief structure 8 are very advantageous. Whereas the relief structure 6 diffracts incident light, relief structure 8 produces diffused dispersion. This ensures that the unchanged markings 3 can be reliably distinguished from the obliterated markings 3' with an optical reading instrument. The information provided by the unchanged markings 3 and the obliterated markings 3' may be read in known manner from the light reflected at the markings 3 and 3'. This is made possible by applying a thin reflective film to the information carrier 2 before or after the relief structure 6 is impressed. It is of course also possible to detect the light transmitted instead of the light reflected.
As compared with the known process of impressing optical markings in a completely smooth, structureless surface, the solution described gives a considerable reduction in the amount of energy required to obliterate the markings 3', and also a greater difference between the optical properties of the obliterated and unobliterated regions.
FIG. 5 shows a typical curve of the tensile strength σB and expansion δg of a thermoplastic material in dependence on the temperature T. The transition from the solid to the thermoelastic range of states at glass transition temperature Tg is characterized by a sharp drop in tensile strength σB and a steep rise in expansion δg. The transition from the thermoelastic to the thermoplastic range takes place at flow temperature Tf. In order to give the information carrier 2 excellent memorizing capability for the first relief structure 5, the second relief structure 6 is advantageously impressed in the carrier 2 in the thermoelastic range. For the same reason the first relief structure 5 is preferably put into the information carrier 2 in the thermoplastic range. To make the first relief structure 5 reappear it is sufficient to heat the information carrier 2 to a temperature in the region of the glass transition temperature Tg ; the energy requirement for obliterating the markings 3' is consequently small.
Both the first relief structure 5 and the second relief structure 6 may be of a type such that they diffract, refract or reflect incident light in a characteristic manner, provided that they differ sufficiently from one another. The fineness of the relief structures may extend from Fresnel structures with a periodicity of about 30 microns and more to diffraction structures and holographic relief structures with a periodicity of about one micron. The first relief structure 5 may act as an additional sign of genuineness to safeguard the document 1 against forgeries.
A particularly small energy requirement for obliteration and a particularly marked difference between the reading signals obtainable at the obliterated markings 3' and the non-obliterated markings 3 are obtained if the first relief structure 5 produces dispersion or a characteristic refraction or reflection of incident light by the laws of geometrical optics, and the second relief structure 6 produces a characteristic diffraction of incident light. FIG. 6 shows a first relief structure 5' of this type, a bevelled profile of sawtooth cross-section. When the second relief structure 6, which may be a phased hologram, a phased diffraction grating, a kinematic shape (kinoform) or the like, is impressed, the first relief structure 5' is converted into an elastic stress field 7' (FIG. 7). The relief structure 8' shown in FIG. 8 and produced by the action of heat reflects incident light in a characteristic way similar to the first relief structure 5'.
Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope and spirit of the invention as defined by the appended claims.

Claims (7)

What is claimed is:
1. A document comprising an information carrier on which information is recorded in the form of optical markings, wherein said information carrier has a shape-memorizing capability to memorize the shape of a relief structure, said capability being operable by supplying energy to said information carrier, thereby producing a change in the shape of said information carrier and of said optical markings.
2. A document according to claim 1 wherein said optical markings are in the form of a second surface relief structure impressed upon a first surface relief structure, and wherein said shape-memorizing capability is an elastic stress field in said information carrier by which stress field said second surface relief structure can be converted into said first surface relief structure which is different from said second surface relief structure, by supplying energy.
3. A document according to claim 2 wherein said information carrier is made of thermoplastic material, and wherein by means of said stress field, said second surface relief structure can be converted into said first surface relief structure by the action of heat.
4. A document according to claim 3 wherein said first surface relief structure causes dispersion, characteristic refraction or characteristic reflection of incident light, and said second surface relief structure produces a characteristic diffraction of incident light.
5. A document according to claim 2, wherein said optical markings are coated with a thin reflective coating.
6. A method of making an optically coded document comprising introducing a first surface relief structure into a thermoplastic information carrier, and subsequently impressing a second surface relief structure into said information carrier in such a way that said first surface relief structure disappears and is converted into an elastic stress field.
7. A method according to claim 6 wherein said first surface relief structure is impressed in said information carrier within the thermoplastic range of the material of said information carrier, and said second surface relief structure is impressed in said information carrier within the thermoelastic range of said material.
US05/848,871 1976-12-21 1977-11-07 Optically coded document and method of making same Expired - Lifetime US4163570A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH16084/76 1976-12-21
CH1608476A CH604279A5 (en) 1976-12-21 1976-12-21

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JP (1) JPS5378897A (en)
BE (1) BE862062A (en)
CH (1) CH604279A5 (en)
DE (1) DE2701175B2 (en)
ES (1) ES465222A1 (en)
FR (1) FR2375691A1 (en)
GB (1) GB1571458A (en)
IT (1) IT1088835B (en)
SE (1) SE418337B (en)

Cited By (97)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4790565A (en) * 1984-10-24 1988-12-13 Steed Signs Pty., Limited Game
GB2221870A (en) * 1988-05-31 1990-02-21 De La Rue Co Plc Security device
US4924078A (en) * 1987-11-25 1990-05-08 Sant Anselmo Carl Identification symbol, system and method
US5109153A (en) * 1990-04-17 1992-04-28 Johnsen Edward L Flash imaging and voidable articles
US5128528A (en) * 1990-10-15 1992-07-07 Dittler Brothers, Inc. Matrix encoding devices and methods
US5200794A (en) * 1989-08-11 1993-04-06 Nhk Spring Co., Ltd. Optical head for an optical authenticity identifing system
US5282651A (en) * 1991-04-15 1994-02-01 Frank Alonso Trading cards and method of concealing and revealing information thereon
US5291006A (en) * 1989-08-11 1994-03-01 Nhk Spring Co., Ltd. Authenticity identifying system for information storage cards
US5347111A (en) * 1991-12-26 1994-09-13 Nhk Spring Co., Ltd. Authenticity identifying structure for an article
US5438403A (en) * 1992-04-28 1995-08-01 Nhk Spring Co., Ltd. Article identification system
US5442433A (en) * 1989-08-11 1995-08-15 Nhk Spring Co., Ltd. Identification system for an article having individually attached patches
US5454598A (en) * 1993-04-19 1995-10-03 Wicker; David M. Tamper and copy protected documents
US5466011A (en) * 1994-04-06 1995-11-14 Cohn; David L. Cable identification system
US5629801A (en) * 1995-06-07 1997-05-13 Silicon Light Machines Diffraction grating light doubling collection system
US5661592A (en) * 1995-06-07 1997-08-26 Silicon Light Machines Method of making and an apparatus for a flat diffraction grating light valve
WO1997031784A2 (en) * 1996-02-16 1997-09-04 Verify First Technologies, Inc. System having thermo-activated pantograph and validation mark
US5704651A (en) * 1995-05-25 1998-01-06 Verify First Technologies, Inc. Counterfeit resistant documents and methods
US5762378A (en) * 1996-02-16 1998-06-09 Verify First Technologies, Inc. Tamper resistant validation marks
US5772248A (en) * 1995-12-07 1998-06-30 Verify First Technologies, Inc. Document with tamper and counterfeit resistant relief markings
US5798743A (en) * 1995-06-07 1998-08-25 Silicon Light Machines Clear-behind matrix addressing for display systems
US5801857A (en) * 1989-09-28 1998-09-01 Gao Gesellschaft Fur Automation Und Organisation Mbh Data carrier having an optically variable element and methods for producing it
US5808797A (en) * 1992-04-28 1998-09-15 Silicon Light Machines Method and apparatus for modulating a light beam
US5841579A (en) * 1995-06-07 1998-11-24 Silicon Light Machines Flat diffraction grating light valve
US5923413A (en) * 1996-11-15 1999-07-13 Interbold Universal bank note denominator and validator
US5982553A (en) * 1997-03-20 1999-11-09 Silicon Light Machines Display device incorporating one-dimensional grating light-valve array
US6064404A (en) * 1996-11-05 2000-05-16 Silicon Light Machines Bandwidth and frame buffer size reduction in a digital pulse-width-modulated display system
US6088102A (en) * 1997-10-31 2000-07-11 Silicon Light Machines Display apparatus including grating light-valve array and interferometric optical system
US6101036A (en) * 1998-06-23 2000-08-08 Silicon Light Machines Embossed diffraction grating alone and in combination with changeable image display
US6130770A (en) * 1998-06-23 2000-10-10 Silicon Light Machines Electron gun activated grating light valve
US6215579B1 (en) 1998-06-24 2001-04-10 Silicon Light Machines Method and apparatus for modulating an incident light beam for forming a two-dimensional image
US6271808B1 (en) 1998-06-05 2001-08-07 Silicon Light Machines Stereo head mounted display using a single display device
US20010022382A1 (en) * 1998-07-29 2001-09-20 Shook James Gill Method of and apparatus for sealing an hermetic lid to a semiconductor die
WO2001091034A1 (en) * 2000-05-23 2001-11-29 Centre National De La Recherche Scientifique (Cnrs) Method for marking a material and method for reading said marking
US6386446B1 (en) * 1998-12-17 2002-05-14 International Business Machines Cirporation Method for use of transaction media encoded with write-and-destroy entries
US20020098610A1 (en) * 2001-01-19 2002-07-25 Alexander Payne Reduced surface charging in silicon-based devices
US20020186448A1 (en) * 2001-04-10 2002-12-12 Silicon Light Machines Angled illumination for a single order GLV based projection system
US20020196492A1 (en) * 2001-06-25 2002-12-26 Silicon Light Machines Method and apparatus for dynamic equalization in wavelength division multiplexing
US20030025984A1 (en) * 2001-08-01 2003-02-06 Chris Gudeman Optical mem device with encapsulated dampening gas
US20030035215A1 (en) * 2001-08-15 2003-02-20 Silicon Light Machines Blazed grating light valve
US20030035189A1 (en) * 2001-08-15 2003-02-20 Amm David T. Stress tuned blazed grating light valve
US6573983B1 (en) 1996-11-15 2003-06-03 Diebold, Incorporated Apparatus and method for processing bank notes and other documents in an automated banking machine
US20030103194A1 (en) * 2001-11-30 2003-06-05 Gross Kenneth P. Display apparatus including RGB color combiner and 1D light valve relay including schlieren filter
US20030208753A1 (en) * 2001-04-10 2003-11-06 Silicon Light Machines Method, system, and display apparatus for encrypted cinema
US20030223675A1 (en) * 2002-05-29 2003-12-04 Silicon Light Machines Optical switch
US6659508B1 (en) * 1999-06-25 2003-12-09 Note Printing Australia Limited Security documents
US20040001264A1 (en) * 2002-06-28 2004-01-01 Christopher Gudeman Micro-support structures
US20040001257A1 (en) * 2001-03-08 2004-01-01 Akira Tomita High contrast grating light valve
US20040008399A1 (en) * 2001-06-25 2004-01-15 Trisnadi Jahja I. Method, apparatus, and diffuser for reducing laser speckle
US20040057101A1 (en) * 2002-06-28 2004-03-25 James Hunter Reduced formation of asperities in contact micro-structures
US6714337B1 (en) 2002-06-28 2004-03-30 Silicon Light Machines Method and device for modulating a light beam and having an improved gamma response
US6712480B1 (en) 2002-09-27 2004-03-30 Silicon Light Machines Controlled curvature of stressed micro-structures
US6728023B1 (en) 2002-05-28 2004-04-27 Silicon Light Machines Optical device arrays with optimized image resolution
US6767751B2 (en) 2002-05-28 2004-07-27 Silicon Light Machines, Inc. Integrated driver process flow
US6801354B1 (en) 2002-08-20 2004-10-05 Silicon Light Machines, Inc. 2-D diffraction grating for substantially eliminating polarization dependent losses
US6800238B1 (en) 2002-01-15 2004-10-05 Silicon Light Machines, Inc. Method for domain patterning in low coercive field ferroelectrics
US6806997B1 (en) 2003-02-28 2004-10-19 Silicon Light Machines, Inc. Patterned diffractive light modulator ribbon for PDL reduction
US6822769B1 (en) 1999-06-01 2004-11-23 De La Rue International Limited Security device
US6822797B1 (en) 2002-05-31 2004-11-23 Silicon Light Machines, Inc. Light modulator structure for producing high-contrast operation using zero-order light
US6829258B1 (en) 2002-06-26 2004-12-07 Silicon Light Machines, Inc. Rapidly tunable external cavity laser
US6865346B1 (en) 2001-06-05 2005-03-08 Silicon Light Machines Corporation Fiber optic transceiver
US6872984B1 (en) 1998-07-29 2005-03-29 Silicon Light Machines Corporation Method of sealing a hermetic lid to a semiconductor die at an angle
US6922273B1 (en) 2003-02-28 2005-07-26 Silicon Light Machines Corporation PDL mitigation structure for diffractive MEMS and gratings
US6922272B1 (en) 2003-02-14 2005-07-26 Silicon Light Machines Corporation Method and apparatus for leveling thermal stress variations in multi-layer MEMS devices
US6928207B1 (en) 2002-12-12 2005-08-09 Silicon Light Machines Corporation Apparatus for selectively blocking WDM channels
US6927891B1 (en) 2002-12-23 2005-08-09 Silicon Light Machines Corporation Tilt-able grating plane for improved crosstalk in 1×N blaze switches
US6934070B1 (en) 2002-12-18 2005-08-23 Silicon Light Machines Corporation Chirped optical MEM device
US6947613B1 (en) 2003-02-11 2005-09-20 Silicon Light Machines Corporation Wavelength selective switch and equalizer
US6956995B1 (en) 2001-11-09 2005-10-18 Silicon Light Machines Corporation Optical communication arrangement
US6956878B1 (en) 2000-02-07 2005-10-18 Silicon Light Machines Corporation Method and apparatus for reducing laser speckle using polarization averaging
US6987600B1 (en) 2002-12-17 2006-01-17 Silicon Light Machines Corporation Arbitrary phase profile for better equalization in dynamic gain equalizer
US6991953B1 (en) 2001-09-13 2006-01-31 Silicon Light Machines Corporation Microelectronic mechanical system and methods
US7027202B1 (en) 2003-02-28 2006-04-11 Silicon Light Machines Corp Silicon substrate as a light modulator sacrificial layer
US7042611B1 (en) 2003-03-03 2006-05-09 Silicon Light Machines Corporation Pre-deflected bias ribbons
US7054515B1 (en) 2002-05-30 2006-05-30 Silicon Light Machines Corporation Diffractive light modulator-based dynamic equalizer with integrated spectral monitor
US7057795B2 (en) 2002-08-20 2006-06-06 Silicon Light Machines Corporation Micro-structures with individually addressable ribbon pairs
US7057819B1 (en) 2002-12-17 2006-06-06 Silicon Light Machines Corporation High contrast tilting ribbon blazed grating
US7068372B1 (en) 2003-01-28 2006-06-27 Silicon Light Machines Corporation MEMS interferometer-based reconfigurable optical add-and-drop multiplexor
US7286764B1 (en) 2003-02-03 2007-10-23 Silicon Light Machines Corporation Reconfigurable modulator-based optical add-and-drop multiplexer
US7391973B1 (en) 2003-02-28 2008-06-24 Silicon Light Machines Corporation Two-stage gain equalizer
US20080212035A1 (en) * 2006-12-12 2008-09-04 Christensen Robert R System and method for aligning RGB light in a single modulator projector
US20080259988A1 (en) * 2007-01-19 2008-10-23 Evans & Sutherland Computer Corporation Optical actuator with improved response time and method of making the same
US20090002644A1 (en) * 2007-05-21 2009-01-01 Evans & Sutherland Computer Corporation Invisible scanning safety system
US7513417B2 (en) 1996-11-15 2009-04-07 Diebold, Incorporated Automated banking machine
US20090168186A1 (en) * 2007-09-07 2009-07-02 Forrest Williams Device and method for reducing etendue in a diode laser
US7559460B2 (en) 1996-11-15 2009-07-14 Diebold Incorporated Automated banking machine
US20090219491A1 (en) * 2007-10-18 2009-09-03 Evans & Sutherland Computer Corporation Method of combining multiple Gaussian beams for efficient uniform illumination of one-dimensional light modulators
US7584883B2 (en) 1996-11-15 2009-09-08 Diebold, Incorporated Check cashing automated banking machine
US20090322740A1 (en) * 2008-05-23 2009-12-31 Carlson Kenneth L System and method for displaying a planar image on a curved surface
US20100078564A1 (en) * 2006-01-31 2010-04-01 Polychromix Corporation Apparatus and method providing a hand-held spectrometer
US8077378B1 (en) 2008-11-12 2011-12-13 Evans & Sutherland Computer Corporation Calibration system and method for light modulation device
US20130285361A1 (en) * 2010-11-02 2013-10-31 Ovd Kinegram Ag Security Element and Method for Producing a Security Element
US8702248B1 (en) 2008-06-11 2014-04-22 Evans & Sutherland Computer Corporation Projection method for reducing interpixel gaps on a viewing surface
US20160140790A1 (en) * 2011-10-04 2016-05-19 Deutsche Post Ag Method and device for marking value labels
US9641826B1 (en) 2011-10-06 2017-05-02 Evans & Sutherland Computer Corporation System and method for displaying distant 3-D stereo on a dome surface
US20220314681A1 (en) * 2019-06-06 2022-10-06 Giesecke+Devrient Currency Technology Gmbh Method for producing an optically variable security element
US11512902B2 (en) 2017-11-01 2022-11-29 Holtec International Flow baffles for shell and tube heat exchangers
US11796255B2 (en) 2017-02-24 2023-10-24 Holtec International Air-cooled condenser with deflection limiter beams

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2483111A1 (en) * 1980-05-21 1981-11-27 Crouzet Sa THERMODESTRUCTIBLE MAGNETIC MEMORY ELEMENT
JPS59134088U (en) * 1983-02-25 1984-09-07 明邦産業株式会社 Shield type book type table clock
JPH0220192U (en) * 1988-07-25 1990-02-09
FR2688614B1 (en) * 1992-03-16 2000-07-28 ELECTRONIC MEMORY CARD WITH DISPLAY OF THE CONSUMPTION OF THE BALANCE AVAILABLE IN ITS MEMORY.

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH574144A5 (en) * 1974-07-19 1976-03-31 Landis & Gyr Ag

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH574144A5 (en) * 1974-07-19 1976-03-31 Landis & Gyr Ag

Cited By (120)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4790565A (en) * 1984-10-24 1988-12-13 Steed Signs Pty., Limited Game
US5612524A (en) * 1987-11-25 1997-03-18 Veritec Inc. Identification symbol system and method with orientation mechanism
US4924078A (en) * 1987-11-25 1990-05-08 Sant Anselmo Carl Identification symbol, system and method
GB2221870A (en) * 1988-05-31 1990-02-21 De La Rue Co Plc Security device
US5200794A (en) * 1989-08-11 1993-04-06 Nhk Spring Co., Ltd. Optical head for an optical authenticity identifing system
US5291006A (en) * 1989-08-11 1994-03-01 Nhk Spring Co., Ltd. Authenticity identifying system for information storage cards
US5442433A (en) * 1989-08-11 1995-08-15 Nhk Spring Co., Ltd. Identification system for an article having individually attached patches
US5801857A (en) * 1989-09-28 1998-09-01 Gao Gesellschaft Fur Automation Und Organisation Mbh Data carrier having an optically variable element and methods for producing it
US6954293B2 (en) 1989-09-28 2005-10-11 GAO Gesellschaft für Automation und Organisation mbH Data carrier having an optically variable element and methods for producing it
US6337752B1 (en) 1989-09-28 2002-01-08 GAO Gesellschaft für Automation und Organisation mbH Data carrier having an optically variable element and methods for producing it
US5109153A (en) * 1990-04-17 1992-04-28 Johnsen Edward L Flash imaging and voidable articles
US5128528A (en) * 1990-10-15 1992-07-07 Dittler Brothers, Inc. Matrix encoding devices and methods
US5282651A (en) * 1991-04-15 1994-02-01 Frank Alonso Trading cards and method of concealing and revealing information thereon
US5347111A (en) * 1991-12-26 1994-09-13 Nhk Spring Co., Ltd. Authenticity identifying structure for an article
US5438403A (en) * 1992-04-28 1995-08-01 Nhk Spring Co., Ltd. Article identification system
US5808797A (en) * 1992-04-28 1998-09-15 Silicon Light Machines Method and apparatus for modulating a light beam
US5454598A (en) * 1993-04-19 1995-10-03 Wicker; David M. Tamper and copy protected documents
US5466011A (en) * 1994-04-06 1995-11-14 Cohn; David L. Cable identification system
US5873604A (en) * 1995-05-25 1999-02-23 Verify First Technologies, Inc. Document security system having thermo-activated pantograph and validation mark
US5704651A (en) * 1995-05-25 1998-01-06 Verify First Technologies, Inc. Counterfeit resistant documents and methods
US5629801A (en) * 1995-06-07 1997-05-13 Silicon Light Machines Diffraction grating light doubling collection system
US5798743A (en) * 1995-06-07 1998-08-25 Silicon Light Machines Clear-behind matrix addressing for display systems
US5841579A (en) * 1995-06-07 1998-11-24 Silicon Light Machines Flat diffraction grating light valve
US5661592A (en) * 1995-06-07 1997-08-26 Silicon Light Machines Method of making and an apparatus for a flat diffraction grating light valve
US5772248A (en) * 1995-12-07 1998-06-30 Verify First Technologies, Inc. Document with tamper and counterfeit resistant relief markings
US5762378A (en) * 1996-02-16 1998-06-09 Verify First Technologies, Inc. Tamper resistant validation marks
WO1997031784A3 (en) * 1996-02-16 1997-11-20 Verify First Technologies Inc System having thermo-activated pantograph and validation mark
WO1997031784A2 (en) * 1996-02-16 1997-09-04 Verify First Technologies, Inc. System having thermo-activated pantograph and validation mark
US6064404A (en) * 1996-11-05 2000-05-16 Silicon Light Machines Bandwidth and frame buffer size reduction in a digital pulse-width-modulated display system
US7559460B2 (en) 1996-11-15 2009-07-14 Diebold Incorporated Automated banking machine
US6774986B2 (en) 1996-11-15 2004-08-10 Diebold, Incorporated Apparatus and method for correlating a suspect note deposited in an automated banking machine with the depositor
US6101266A (en) * 1996-11-15 2000-08-08 Diebold, Incorporated Apparatus and method of determining conditions of bank notes
US6573983B1 (en) 1996-11-15 2003-06-03 Diebold, Incorporated Apparatus and method for processing bank notes and other documents in an automated banking machine
US7513417B2 (en) 1996-11-15 2009-04-07 Diebold, Incorporated Automated banking machine
US7584883B2 (en) 1996-11-15 2009-09-08 Diebold, Incorporated Check cashing automated banking machine
US5923413A (en) * 1996-11-15 1999-07-13 Interbold Universal bank note denominator and validator
US5982553A (en) * 1997-03-20 1999-11-09 Silicon Light Machines Display device incorporating one-dimensional grating light-valve array
US6088102A (en) * 1997-10-31 2000-07-11 Silicon Light Machines Display apparatus including grating light-valve array and interferometric optical system
US6271808B1 (en) 1998-06-05 2001-08-07 Silicon Light Machines Stereo head mounted display using a single display device
US6101036A (en) * 1998-06-23 2000-08-08 Silicon Light Machines Embossed diffraction grating alone and in combination with changeable image display
US6130770A (en) * 1998-06-23 2000-10-10 Silicon Light Machines Electron gun activated grating light valve
US6215579B1 (en) 1998-06-24 2001-04-10 Silicon Light Machines Method and apparatus for modulating an incident light beam for forming a two-dimensional image
US6764875B2 (en) 1998-07-29 2004-07-20 Silicon Light Machines Method of and apparatus for sealing an hermetic lid to a semiconductor die
US20010022382A1 (en) * 1998-07-29 2001-09-20 Shook James Gill Method of and apparatus for sealing an hermetic lid to a semiconductor die
US6872984B1 (en) 1998-07-29 2005-03-29 Silicon Light Machines Corporation Method of sealing a hermetic lid to a semiconductor die at an angle
US6386446B1 (en) * 1998-12-17 2002-05-14 International Business Machines Cirporation Method for use of transaction media encoded with write-and-destroy entries
US6822769B1 (en) 1999-06-01 2004-11-23 De La Rue International Limited Security device
US6659508B1 (en) * 1999-06-25 2003-12-09 Note Printing Australia Limited Security documents
US6956878B1 (en) 2000-02-07 2005-10-18 Silicon Light Machines Corporation Method and apparatus for reducing laser speckle using polarization averaging
FR2809517A1 (en) * 2000-05-23 2001-11-30 Centre Nat Rech Scient METHOD FOR MARKING A MATERIAL AND METHOD FOR READING THE MARKING
WO2001091034A1 (en) * 2000-05-23 2001-11-29 Centre National De La Recherche Scientifique (Cnrs) Method for marking a material and method for reading said marking
US20020098610A1 (en) * 2001-01-19 2002-07-25 Alexander Payne Reduced surface charging in silicon-based devices
US7177081B2 (en) 2001-03-08 2007-02-13 Silicon Light Machines Corporation High contrast grating light valve type device
US20040001257A1 (en) * 2001-03-08 2004-01-01 Akira Tomita High contrast grating light valve
US20030208753A1 (en) * 2001-04-10 2003-11-06 Silicon Light Machines Method, system, and display apparatus for encrypted cinema
US20020186448A1 (en) * 2001-04-10 2002-12-12 Silicon Light Machines Angled illumination for a single order GLV based projection system
US6707591B2 (en) 2001-04-10 2004-03-16 Silicon Light Machines Angled illumination for a single order light modulator based projection system
US6865346B1 (en) 2001-06-05 2005-03-08 Silicon Light Machines Corporation Fiber optic transceiver
US6747781B2 (en) 2001-06-25 2004-06-08 Silicon Light Machines, Inc. Method, apparatus, and diffuser for reducing laser speckle
US6782205B2 (en) 2001-06-25 2004-08-24 Silicon Light Machines Method and apparatus for dynamic equalization in wavelength division multiplexing
US20020196492A1 (en) * 2001-06-25 2002-12-26 Silicon Light Machines Method and apparatus for dynamic equalization in wavelength division multiplexing
US20040008399A1 (en) * 2001-06-25 2004-01-15 Trisnadi Jahja I. Method, apparatus, and diffuser for reducing laser speckle
US20030025984A1 (en) * 2001-08-01 2003-02-06 Chris Gudeman Optical mem device with encapsulated dampening gas
US6829092B2 (en) 2001-08-15 2004-12-07 Silicon Light Machines, Inc. Blazed grating light valve
US20030035189A1 (en) * 2001-08-15 2003-02-20 Amm David T. Stress tuned blazed grating light valve
US20030035215A1 (en) * 2001-08-15 2003-02-20 Silicon Light Machines Blazed grating light valve
US20030223116A1 (en) * 2001-08-15 2003-12-04 Amm David T. Blazed grating light valve
US6991953B1 (en) 2001-09-13 2006-01-31 Silicon Light Machines Corporation Microelectronic mechanical system and methods
US7049164B2 (en) 2001-09-13 2006-05-23 Silicon Light Machines Corporation Microelectronic mechanical system and methods
US6956995B1 (en) 2001-11-09 2005-10-18 Silicon Light Machines Corporation Optical communication arrangement
US20030103194A1 (en) * 2001-11-30 2003-06-05 Gross Kenneth P. Display apparatus including RGB color combiner and 1D light valve relay including schlieren filter
US6800238B1 (en) 2002-01-15 2004-10-05 Silicon Light Machines, Inc. Method for domain patterning in low coercive field ferroelectrics
US6767751B2 (en) 2002-05-28 2004-07-27 Silicon Light Machines, Inc. Integrated driver process flow
US6728023B1 (en) 2002-05-28 2004-04-27 Silicon Light Machines Optical device arrays with optimized image resolution
US20030223675A1 (en) * 2002-05-29 2003-12-04 Silicon Light Machines Optical switch
US7054515B1 (en) 2002-05-30 2006-05-30 Silicon Light Machines Corporation Diffractive light modulator-based dynamic equalizer with integrated spectral monitor
US6822797B1 (en) 2002-05-31 2004-11-23 Silicon Light Machines, Inc. Light modulator structure for producing high-contrast operation using zero-order light
US6829258B1 (en) 2002-06-26 2004-12-07 Silicon Light Machines, Inc. Rapidly tunable external cavity laser
US20040001264A1 (en) * 2002-06-28 2004-01-01 Christopher Gudeman Micro-support structures
US6813059B2 (en) 2002-06-28 2004-11-02 Silicon Light Machines, Inc. Reduced formation of asperities in contact micro-structures
US6714337B1 (en) 2002-06-28 2004-03-30 Silicon Light Machines Method and device for modulating a light beam and having an improved gamma response
US20040057101A1 (en) * 2002-06-28 2004-03-25 James Hunter Reduced formation of asperities in contact micro-structures
US6908201B2 (en) 2002-06-28 2005-06-21 Silicon Light Machines Corporation Micro-support structures
US6801354B1 (en) 2002-08-20 2004-10-05 Silicon Light Machines, Inc. 2-D diffraction grating for substantially eliminating polarization dependent losses
US7057795B2 (en) 2002-08-20 2006-06-06 Silicon Light Machines Corporation Micro-structures with individually addressable ribbon pairs
US6712480B1 (en) 2002-09-27 2004-03-30 Silicon Light Machines Controlled curvature of stressed micro-structures
US6928207B1 (en) 2002-12-12 2005-08-09 Silicon Light Machines Corporation Apparatus for selectively blocking WDM channels
US6987600B1 (en) 2002-12-17 2006-01-17 Silicon Light Machines Corporation Arbitrary phase profile for better equalization in dynamic gain equalizer
US7057819B1 (en) 2002-12-17 2006-06-06 Silicon Light Machines Corporation High contrast tilting ribbon blazed grating
US6934070B1 (en) 2002-12-18 2005-08-23 Silicon Light Machines Corporation Chirped optical MEM device
US6927891B1 (en) 2002-12-23 2005-08-09 Silicon Light Machines Corporation Tilt-able grating plane for improved crosstalk in 1×N blaze switches
US7068372B1 (en) 2003-01-28 2006-06-27 Silicon Light Machines Corporation MEMS interferometer-based reconfigurable optical add-and-drop multiplexor
US7286764B1 (en) 2003-02-03 2007-10-23 Silicon Light Machines Corporation Reconfigurable modulator-based optical add-and-drop multiplexer
US6947613B1 (en) 2003-02-11 2005-09-20 Silicon Light Machines Corporation Wavelength selective switch and equalizer
US6922272B1 (en) 2003-02-14 2005-07-26 Silicon Light Machines Corporation Method and apparatus for leveling thermal stress variations in multi-layer MEMS devices
US6922273B1 (en) 2003-02-28 2005-07-26 Silicon Light Machines Corporation PDL mitigation structure for diffractive MEMS and gratings
US7391973B1 (en) 2003-02-28 2008-06-24 Silicon Light Machines Corporation Two-stage gain equalizer
US6806997B1 (en) 2003-02-28 2004-10-19 Silicon Light Machines, Inc. Patterned diffractive light modulator ribbon for PDL reduction
US7027202B1 (en) 2003-02-28 2006-04-11 Silicon Light Machines Corp Silicon substrate as a light modulator sacrificial layer
US7042611B1 (en) 2003-03-03 2006-05-09 Silicon Light Machines Corporation Pre-deflected bias ribbons
US20100078564A1 (en) * 2006-01-31 2010-04-01 Polychromix Corporation Apparatus and method providing a hand-held spectrometer
US7791027B2 (en) 2006-01-31 2010-09-07 Ahura Scientific Inc. Apparatus and method providing a hand-held spectrometer
US20080212035A1 (en) * 2006-12-12 2008-09-04 Christensen Robert R System and method for aligning RGB light in a single modulator projector
US7891818B2 (en) 2006-12-12 2011-02-22 Evans & Sutherland Computer Corporation System and method for aligning RGB light in a single modulator projector
US20080259988A1 (en) * 2007-01-19 2008-10-23 Evans & Sutherland Computer Corporation Optical actuator with improved response time and method of making the same
US20090002644A1 (en) * 2007-05-21 2009-01-01 Evans & Sutherland Computer Corporation Invisible scanning safety system
US20090168186A1 (en) * 2007-09-07 2009-07-02 Forrest Williams Device and method for reducing etendue in a diode laser
US20090219491A1 (en) * 2007-10-18 2009-09-03 Evans & Sutherland Computer Corporation Method of combining multiple Gaussian beams for efficient uniform illumination of one-dimensional light modulators
US20090322740A1 (en) * 2008-05-23 2009-12-31 Carlson Kenneth L System and method for displaying a planar image on a curved surface
US8358317B2 (en) 2008-05-23 2013-01-22 Evans & Sutherland Computer Corporation System and method for displaying a planar image on a curved surface
US8702248B1 (en) 2008-06-11 2014-04-22 Evans & Sutherland Computer Corporation Projection method for reducing interpixel gaps on a viewing surface
US8077378B1 (en) 2008-11-12 2011-12-13 Evans & Sutherland Computer Corporation Calibration system and method for light modulation device
US20130285361A1 (en) * 2010-11-02 2013-10-31 Ovd Kinegram Ag Security Element and Method for Producing a Security Element
US20160140790A1 (en) * 2011-10-04 2016-05-19 Deutsche Post Ag Method and device for marking value labels
US9641826B1 (en) 2011-10-06 2017-05-02 Evans & Sutherland Computer Corporation System and method for displaying distant 3-D stereo on a dome surface
US10110876B1 (en) 2011-10-06 2018-10-23 Evans & Sutherland Computer Corporation System and method for displaying images in 3-D stereo
US11796255B2 (en) 2017-02-24 2023-10-24 Holtec International Air-cooled condenser with deflection limiter beams
US11512902B2 (en) 2017-11-01 2022-11-29 Holtec International Flow baffles for shell and tube heat exchangers
US20220314681A1 (en) * 2019-06-06 2022-10-06 Giesecke+Devrient Currency Technology Gmbh Method for producing an optically variable security element
US11807029B2 (en) * 2019-06-06 2023-11-07 Giesecke+Devrient Currency Technology Gmbh Method for producing an optically variable security element

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IT1088835B (en) 1985-06-10
FR2375691B1 (en) 1981-08-28
JPS553755B2 (en) 1980-01-26
ES465222A1 (en) 1978-09-16
GB1571458A (en) 1980-07-16
DE2701175A1 (en) 1978-06-22
FR2375691A1 (en) 1978-07-21
JPS5378897A (en) 1978-07-12
SE7714165L (en) 1978-06-22
CH604279A5 (en) 1978-08-31
DE2701175C3 (en) 1981-01-22
BE862062A (en) 1978-04-14
DE2701175B2 (en) 1980-05-08
SE418337B (en) 1981-05-18

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